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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b4b32cdf62fdc7bc81d4f758fa6905538c6e51ecffdb364cdb645da0fb1ea1a7' 
  AND token = 'H9d37zgpiW8Sno6J5SRmNJ6EtKcgONTtKNM84xLJ6LQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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