SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7eca1ecec4985894ebceac0c7706a28ca1089c80f255bfc8daa92efb2b145a3' 
  AND token = 'aeafd8wZYBvSMKlsi/wprBuN3uchdRfzVhYquDWmdp8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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