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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56e3764170a39fdcf8c33d2ccf9b4b44831ac0ff0fd6349e6fbc8e503cb7c597' 
  AND token = 'hn5BnxN+Vj3cJEqOWIR2tOlM/VWJ21+xY0+5eD3aBuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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