SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e83feec5ba0b95281539fb4673ba4986500a65e08873c642cad79d2d2e6f3e39' 
  AND token = 'CVq8MGsAgruhaMoFemuPooa/KubfRKlurAySAFWdrEI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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