SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef70dda929fca594f4969e60344c5d696246dbf7d0f5cd352403865802da84a2' 
  AND token = 'udZwrvIV+hQbawG2chdLHANARgVBigglFEe4qr/sYyw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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