SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b2753cb71344683f5a1d9f2d823712568f397b60dfc2764f84172bc2087b4f4' 
  AND token = '0+n0REFgpyzYEUtga24Psx4nfv4OBbTofRdlpD3mAj0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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