SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56df2172ff3ee1879dce8823a1fbfe0a79c7ffaba6e5a75bd7cf5af766129512' 
  AND token = '69Mna2ptBoDETMzny/QEolUietkLk50flJoVbhYfAXE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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