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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6511b686ea8c85759e76d46a733d489df6bee294aff1fbb9858e8e0af368d5ae' 
  AND token = 'nWBuaqcYemtVv5zDImtEWT+UEUrWHfcZORb54B0F6i8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}