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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '42e10136932cc145c6e65d802959a9b81ee45493e5c4f3e5e5d159598acd57cf' 
  AND token = 'uL4gwbLWTD4BVYFMWxna3Bpz5BdJIYv7l/OI+ym2PAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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