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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '503cdfe3734354116dc74ab26e2568eab03ba616f9d8b0df0229489c271a2aaa' 
  AND token = 'mk1bxuSJMrQtL9eMVHqlzv8AlPB5FUhkYrD0zX4/aeo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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