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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4e21bb101717a3c0f03c084922624f5c1f592af9ad84e2bacb29af3324025c68' 
  AND token = 'b3XeSw6qnIr+KADYtZ2FiEhFbI81vbnnrVZ8SIu9YJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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