SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f6b3e8f305373dffe26925ba973dc9c4b364ad64074dd0b294428938d5db823' 
  AND token = 'GIVoOFLc+zMv/bAKhiL8R0sXoj1W+WMdajqJ+M0BBrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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