SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be8f41d97d1c990e1b8a16fcac2e00f0f91e5c5f99269105ee75989ca615f7be' 
  AND token = '9A4rEjXMt27dLUqgeHaMU9Z90TW4a36bcwIVNz+Lbk4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}