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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9034a4f0aad6481b4fe50a9017283e9189351e5c282bd1d73d0ab3ba16e6218' 
  AND token = 'm5WzJn1BQdHdrB9J4d8VAwl0IOm7WyoqDOZR4oLB+J4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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