SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ac70cffd6fb1dba89e6dab70ea86af53789e19e86ebba0aba5479085f129259' 
  AND token = '+EWhgGVB8pGVncn9QKcnNioAJlbxC21rNMwGMII48Ek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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