SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de6edc75989bc26bdbac66ff9c2a3d75b0eab18de722118a225164e596b451ac' 
  AND token = 'xB4eRt+rOjZwwcPfUkjrHmnzfCjJQSEd/VQoVvbvDPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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