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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6bccd1ca3a4114351677cb6b454d2e3eee92c860fa0fcda13b6dfb98d69a00a' 
  AND token = '/OntRBVxwG//m/beW0I1EcG5FZNujynuROqd7xsA+NQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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