SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2052a4c809085c410c039b96c98d93d1528a8c616b37b08739d27552e0af79c5' 
  AND token = '5QkSvO2aqzvPbaMIMzS52cheuwdCElWFTWlxbBWJFxQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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