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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b2e8c8df6dd6cacd5d16df875a2aece5f6563c9f78c184f4317a506eb08d167d' 
  AND token = 'iLDfr9LdDuUcMDgCE0JYdTOKS85B2q/zbFlJLmRNqns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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