SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da553dc229cdaba2a9aed64f4552463783d3bd6b838e487db8b98b4a7a3d5855' 
  AND token = '/cNwpX+V2DfkqgKFoaRx+Gzo10Osve1h3Xsye+Ej5hg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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