SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4c070c95a959521402fbd80d6ada606a707de926817913b1edbc90df518c5eb' 
  AND token = '0zGRrSebncaNmtAWPnOHk3fbGPY1zzOoQ4UBrrJdQT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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