SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4eabc15647b26c94f2a1e741897a996f355bf0270907d9d453ee05746cf2335f' 
  AND token = 'DxKnkHDJucEYBDNRRbIpm513/LpWhZzK81BHWtvoNpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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