SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1342b9b37def8fb486640f4b9dae5f872416d2c30966168616402840f8dcced0' 
  AND token = 'he13qOZFU5aGiC/LoDVrVSe+pssmcwhtjNQV5qbo54g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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