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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f973f1afa312fd1a9e60508175af52509379c1bfaada13a7283538e78fe95ac2' 
  AND token = 'uV+Ys6+wqOMwjdTsERQkG7hx01tE8nBZQWkLJaphMfg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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