SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c27b818a96ddcb62e3de73c48fabfeb22c38fc81394e2e9b2666e24c64ed2bca' 
  AND token = 'PE1UuNdFAEHtbl6J+fw+g2JDlW2wn2SzbNr4dlWF/fA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}