SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe45c2e23a56860e1e5b4afd8207c41a023610980ce245fd52d920ab7445a646' 
  AND token = '68supXFmG8Vv8bDvR9OcMHhouiZYb3g3aotxWLzTm50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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