SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0c126f3f4415ea235e25871c8c8a9dd842c88e060f44dd79d52f206d183d420' 
  AND token = 'r+8T6I7SNpi2xCJthnK54vq744f6yYjQms+auBP1YBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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